Fabrication of InP-based optoelectronic integrated circuit (OEIC) photoreceivers using shared layer integration of heterojunction bipolar transistors and refracting-facet photodiodes

Abstract

InP-based monolithic photoreceivers have been fabricated using a shared layer integration scheme of refracting-facet photodiodes (RFPDs) and heterojunction bipolar transistors (HBTs). An HBT was fabricated using a self-aligned emitter-base process and nonalloyed metallization of the emitter, base and collector ohmic contacts. The fabricated 2 x 10 mum(2) emitter HBT exhibited a maximum current gain of 40. The maximum cutoff frequencies of this HBT were measured to be f(T) = 79 GHz and f(max) = 143 GHz at I-C = 19 mA and V-CE = 1.5 V, respectively. An RFPD was fabricated using the base-collector junction layers of the HBT based on the selective wet chemical etching characteristics of InP and InGaAs layers. The fabricated RFPD showed a 37% increased optical responsivity of 0.48 A/W compared to the fabricated surface-illuminated photodiode using the same photoreceiver epitaxial layer. The full width at half maximum (FWHM) of the fabricated RFPD was determined to be 24 ps using the standard 50 Omega system load. The fabricated three-stage transimpedance amplifier (TIA) showed a transimpedance gain of 46 dBOmega and a -3 dB bandwidth of 12 GHz. The fabricated monolithic RFPD/HBT photoreceiver has demonstrated a -3 dB optical bandwidth of 6.9 GHz.